Salk scientists create the world’s first human/monkey chimeras in China

Scientists at the world-famous Salk Institute have been at work creating embryos in China that are part human, part monkey in a first step toward determining the feasibility of growing organs for human transplants in primates.

Spain’s El Pais talked with Salk investigator Juan Carlos Izpisúa Belmonte — an internationally acclaimed scientist named one of Time magazine’s 50 most influential people in healthcare for 2018 for his work on chimeras.
Izpisúa had earlier been engaged in creating human/pig chimeras with the same goal but had little success with their model, which developed with an overwhelming imbalance of pig versus human cells. He had more success in creating chimeras using cells of similar species, specifically a mouse/rat approach.

In this latest case, explains El Pais, investigators from Salk teamed with scientists from Murcia Catholic University in Spain. Together they worked to deactivate genes in monkey embryos needed for organ development and then injected human stem cells, looking for them to do their work in developing human organs in the monkey embryo. The project never went past the embryo stage, though, and was performed in China to circumvent any legal restrictions.
Four years ago, the NIH stopped accepting grant applications seeking funds for projects like these — infusing human stem cells into primate embryos. That’s been under review, but so far there’s been no change in the official stance.

Estrella Núñez, the vice-chancellor at UCAM, told the Spanish newspaper that the initial results were “very promising.” But others are simply alarmed.

“What happens if the stem cells escape and form human neurons in the brain of the animal?” asks Ángel Raya, the director of the Barcelona Regenerative Medicine Center. “Would it have consciousness? And what happens if these stem cells turn into sperm cells?”
Núñez, though, says they have a built-in self-destruct mechanism that would prevent that from happening.

Pablo Ross, a veterinary researcher at the University of California, Davis who worked on the human/pig chimeras with Salk investigators, told MIT Technology Review the work faces big challenges when it comes to transplant organs.

“I always made the case that it doesn’t make sense to use a primate for that. Typically they are very small, and they take too long to develop,” he says.

Salk scientists create the world’s first human/monkey chimeras in China — cue the controversy